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Production of the antibiotic secondary metabolite solanapyrone A by the fungal plant pathogen Ascochyta rabiei during fruiting body formation in saprobic growth
Author(s) -
Kim Wonyong,
Park JeongJin,
Dugan Frank M.,
Peever Tobin L.,
Gang David R.,
Vandemark George,
Chen Weidong
Publication year - 2017
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.13673
Subject(s) - biology , phytotoxin , fungus , secondary metabolite , secondary metabolism , ascochyta , bipolaris , pathogenic fungus , botany , pathogen , microbiology and biotechnology , colletotrichum , polyketide synthase , plant use of endophytic fungi in defense , polyketide , gene , biosynthesis , toxin , biochemistry , blight
Summary Fungi are noted producers of a diverse array of secondary metabolites, many of which are of pharmacological importance. However, the biological roles of the vast majority of these molecules during the fungal life cycle in nature remain elusive. Solanapyrones are polyketide‐derived secondary metabolites produced by diverse fungal species including the plant pathogen Ascochyta rabiei . This molecule was originally thought to function as a phytotoxin facilitating pathogenesis of A. rabiei . Chemical profiling and gene expression studies showed that solanapyrone A was specifically produced during saprobic, but not parasitic growth of A. rabiei . Expression of the gene encoding the final enzymatic step in solanapyrone biosynthesis was specifically associated with development of the asexual fruiting bodies of the fungus on certain substrates. In confrontation assays with saprobic fungi that were commonly found in chickpea debris in fields, A. rabiei effectively suppressed the growth of all competing fungi, such as Alternaria , Epicoccum and Ulocladium species. Solanapyrone A was directly detected in the inhibitory zone using a MALDI‐imaging mass spectrometry, and the purified compound showed significant antifungal activities against the potential saprobic competitors. These results suggest that solanapyrone A plays an important role for competition and presumably the survival of the fungus.